It is known to use vehicles as probes for measuring traffic conditions in real-time. Each such probe vehicle is equipped with position-determining and communication equipment in order to provide such data as, for example, the vehicle's time, speed, position, and heading, which can then be used to estimate such factors of interest as travel time and traffic speed.
A map segment corresponds to a portion of a road, or one side of the road if the road is divided, lying generally between intersections with other roads or features, such as, for example, geopolitical or other boundaries. Map segments are defined by a map database. The travel time along each map segment is estimated based upon the reported speeds of all probe vehicles traveling on that map segment. Unfortunately, because probe vehicles are distributed substantially randomly, individual map segments may at times be devoid of probe vehicles, such that the needed speed information is not available. This is especially true when there is low probe vehicle penetration and at off-peak times.
For this and other reasons, a need exists for an improved method of collecting traffic data.